In the new document, retired FBI agent Gregg McCrary declares of Hillegas: “I have seen no evidence that he offered an alibi or any sort of statement regarding his activities from October 31, 2005, to November 3, 2005.

“Nor have I seen any evidence that the authorities ever asked him to do so.”

It also transpires that Hillegas was the first person to direct the police to Halbach’s car as he headed up the initial volunteer search party.

McCrary adds: “Mr Hillegas injected himself into the police investigation by taking an active role in the volunteer search.

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Hillegas, who lived near Halbach and was unemployed in 2005, was also found in court to have been an abusive partner and injured his right hand around the time of the crime.

To top it all, Hillegas was permitted to access Steven Avery’s property during the police investigation by giving the false name Kilgus.

Currently Avery is serving his sentence at Wisconsin’s Waupun Correctional Institution and has now been fighting for his freedom for almost 12 years.

Last year his nephew Brendan Dassey — sent down for aiding Avery in killing Halbach — had his conviction for rape and murder overturned, but the state blocked his release, so his appeal is yet to be resolved.

One of the most compelling points highlighted in Making A Murderer was the fact that a vial of Avery’s blood, stored in a locker since 1985 when he was charged with sexual assault, was found with holes in the lid, years after Teresa’s murder.

It contained traces of EDTA, which helps stop blood drying, suggesting it may have been used to plant Avery’s blood in Halbach’s car.

A second series of the show is set to arrive later this year, with Netflix boss Cindy Holland saying in January: “The story is still ongoing, so you will see new episodes coming sometime this year as this story continues to unfold.”